1. Field
An aspect of embodiments according to the present invention relates to an organic light emitting display device.
2. Description of Related Art
Recently, there have been developed various types of flat panel display devices that are lighter in weight and smaller in volume than cathode ray tubes.
Among these flat panel display devices, an organic light emitting display device displays images using organic light emitting diodes (OLEDs) that are self-luminescent elements. The organic light emitting display device has come into the spotlight as a next-generation display device because of its excellent luminance and color purity.
Organic light emitting display devices can be classified as a passive matrix type organic light emitting display device or an active matrix type organic light emitting display device, depending on a method of driving the OLEDs.
Among these organic light emitting display devices, the active matrix type organic light emitting display device is used in portable display devices and the like because of its low power consumption.
Each pixel of the active matrix type organic light emitting display device includes an OLED, a switching transistor for driving the OLED, a driving transistor, a storage capacitor, and may also include other components.
However, the active matrix type organic light emitting display device might not display an image with desired luminance due to a luminance difference between pixels, which may occur due to a drift of threshold voltages of driving transistors, and due to the efficiency change according to the degradation of the OLED.
Because a turn-on state of the driving transistor is continuously maintained by a voltage stored in the storage capacitor during the light emitting period of the pixel after application of a data voltage, the drift of the threshold voltage of the driving transistor may be caused by the gradual degradation of the driving transistor. Therefore, the drift of the threshold voltage of the driving transistor may become a factor that causes the operation of the driving transistor to be unstable.